4.2 Nerves CTD

Question 1

What is a nerve plexus? Why are they important?

Answer 1

– interlacing nerve networks grouped by body regions
Blending of nerve fibers from the ventral rami from adjacent spinal nerves
Purpose: areas receive nerve supply from more than one spinal nerve
limits the loss of complete region if a nerve is damaged

Question 2

What do nerve plexuses attach to?

Answer 2

Ventral rami of spinal nerves

Question 3

What are the nerve plexuses? Where are they?

Answer 3

Cervical Plexus (C1-C4) 
Brachial Plexus (C5 – T1) 
Lumbar Plexus (L1-L5) 
Sacral Plexus (L4-S4)

Question 4

What is the cervical plexus?

Answer 4

10+ nerves that innervate skin and muscles of the neck and shoulder

example:
Phrenic nerve – controls diaphragm
branches from C3,4,5 keeps the diaphragm “alive”
Fractures above the C3 level - respiratory arrest

Question 5

Where is the brachial plexus? What does it innervate? Major nerves?

Answer 5

C5-T1
Innervates pectoral girdle and arms
Convergences and divisions:
Trunks
Cords
Branches
major nerves:
Musculocutaneous
Median
Axillary
Radial
Ulnar

Question 6

What does the musculocutaneous nerve innervate?

Answer 6

supplies anterior arm - biceps brachii, coracobrachialis, brachialis muscles
skin of lateral forearm

Question 7

What does the ulnar nerve innervate?

Answer 7

supplies some flexors of the forearm, medial hand, ½ ring finger to pinky
skin of medial palm, ½ ring finger to pinky

Question 8

What does the median nerve innervate?

Answer 8

supplies most flexors of the forearm, lateral palm, thumb to ½ ring finger
skin of lateral palm, thumb to ½ ring finger

Question 9

What does the radial nerve innervate?

Answer 9

posterior arm, posterior extensors of forearm

skin of posterior arm

Question 10

What does the axillary nerve innervate?

Answer 10

supplies deltoid and teres minor muscles

skin of shoulder

Question 11

What is carpal tunnel? What nerve is involved?

Answer 11

occurs when the connective tissue between the carpal bones and the flexor retinaculum becomes inflamed and compresses tendons and a nearby nerve
Median nerve (brachial plexus)

Question 12

What does the lumbar plexus innervate, in general? What are it’s major nerves?

Answer 12

Innervates lower abdominal, medial and anterior portions of the thigh
Femoral nerve
Obturator nerve

Question 13

What does the femoral nerve innervate?

Answer 13

anterior, inferior, medial thigh skin sensation and anterior thigh muscles (quadriceps femoris, sartorius, iliopsoas)

Question 14

What does the obturator nerve innervate?

Answer 14

medial thigh skin sensation and medial thigh muscles (adductors)

Question 15

In general, what does the sacral plexus innervate?

Answer 15

skin and muscles of gluteal region, pelvis, perineum, posterior thigh, leg and foot

Question 16

What doe the superior and inferior gluteal nerves innervate?

Answer 16

Superior Gluteal Nerve: gluteus medius, minimus and tensor fascia latae
Inferior Gluteal Nerve: gluteus maximus

Question 17

What are the branches of the sciatic nerve?

Answer 17

Tibial Nerve: posterior thigh (all except biceps femoris short head), plantar and digital flexors of posterior leg and foot
Common Peroneal Nerve ( = Common Fibular Nerve): biceps femoris short head
Superficial Peroneal Nerve ( = Superficial Fibular Nerve): fibularis longus and brevis, skin of dorsum of foot
Deep Peroneal Nerve ( = Deep Fibular Nerve): anterior extensors (dorsiflexors) of leg and foot, skin between digit 1-2.

Question 18

What does the pudental nerve innervate?

Answer 18

perineum, external anal sphincter, external urethral sphincter, skin of external genitalia

Question 19

What is central cord syndrome?

Answer 19

compression of neurons within center of spinal cord
motor dysfunction, variable sensory loss, variable bladder function loss
common with cervical hyperextension

Question 20

What is anterior spinal artery syndrome?

Answer 20

loss of blood flow to anterior 2/3 of spinal cord, ischemia, infarction
intervertebral disc herniation, fracture, blocked aortic blood flow

Question 21

What is Brown-Sequard syndrome?

Answer 21

hemisection of the spinal cord, damage of ascending and descending tracts on one side of spinal cord
paralysis or loss of sensation, depending on specific pathways lesioned

Question 22

What is conus medullaris syndrome?

Answer 22

injury to lower spinal cord, fractured L1/L2
urinary retention, erectile dysfunction, constipation, relaxed anal sphincter, loss of anal and bulbocavernosus reflex, inguinal sensation loss, motor weakness

Question 23

What is cauda equina syndrome?

Answer 23

compression of bilateral nerve roots of lumbosacral region due to fracture of lumbar spine, sacrum, or acute herniated disc
motor and sensory loss variable, major sign is incontinence